Control devices

ABSTRACT

Safety lever for the power-shift transmission of a tractor, in which the safety lever can be moved to a transmission-unlocking position wherein the safety lever intervenes adjacent the tractor operator&#39;&#39;s seat to block the exit of the operator from the tractor, and in which the safety lever can be moved to a locking position wherein the safety lever no longer intervenes, but at the same time either retains the transmission locked in neutral position or forces the transmission to take a neutralized setting and thereafter causes the transmission to be retained in that setting, for safety of the operator while exiting from the tractor.

United States Patent Bradshaw 51 Sept. 19,1972

[ CONTROL DEVICES [21] Appl. No.: 7,318

Related US. Application Data [62] Division of Ser. No. 760,904, Sept.19, 1968,

Pat. No. 3,523,588.

[52] US. Cl ..74/491 [51] Int. Cl. ..G05g 5/08 [58] Field ofSearch....74/491, 473 R, 481; 180/824,

[56] References Cited UNITED STATES PATENTS 1,664,042 3/1928 McGinley..l80/82.4 UX 3,431,792 3/1969 Smith ..74/481 Primary Examiner-MiltonKaufman Attorney-Floyd B. Harman [57] ABSTRACT Safety lever for thepower-shift transmission of a tractor, in which the safety lever can bemoved to a transmission-unlocking position wherein the safety leverintervenes adjacent the tractor operator's seat to block the exit of theoperator from the tractor, and in which the safety lever can be moved toa locking position wherein the safety lever no longer intervenes, but atthe same time either retains the transmission locked in neutral positionor forces the transmission to take a neutralized setting and thereaftercauses the transmission to be retained in that setting, for safety ofthe operator while exiting from the tractor.

4 Claims, 3 Drawing Figures CONTROL DEVICES This application is adivision of application Ser. No. 760,904, filed Sept. 19, 1968, now U.S.Pat. No. 3,523,588 granted Aug. 11, 1970.

This invention relates to control devices and more particularly tocontrol devices which are suitable for use with fluid-operated systems,i.e. hydraulic or pneumatic systems, for example a vehicle hydraulictransmission system including hydraulically operable clutches.

It is known to provide locking means for locking a control device in aneutral or non-operating position, for example in a crawler tractorwhich is equipped with a power shift transmission utilizing a torqueconverter and hydraulically actuatable forward and reverse clutches.Such a locking means positively retains the transmission control leverin a neutral position at which both the forward and reverse clutches aredisengaged. In this way unintentional movement of the tractor as theresult of some accidental operation of the control lever is prevented.

it is a main object of the present invention to provide an improvedcontrol device which includes a locking means capable of ensuring thatefl'ective locking of the control device in a neutral position takesplace whenever the locking means is operated.

According to the present invention there is provided a control devicefor a fluid-operated system comprising a control member having at leastone operating .position and a neutral position, and a locking meanswhich is arranged to lock the control member in the neutral position,and which, if moved to its locking position when the control member isin an operating position, acts to return the control member to theneutral position and to lock the control member in the neutral position.

In accordance with the present invention, therefore, if the controldevice is to be locked when the control member is in an operatingposition and therefore displaced from the neutral position, two-stageoperation involving movement of both the control member and the lockingmember is avoided.

As already indicated the control device of the present invention isparticularly suited for use in a vehicle having an hydraulictransmission. According to this aspect of the present invention,therefore, there is provided a vehicle including an hydraulictransmission having a plurality of hydraulically operable clutches forcausing forward and reverse movement of the vehicle, and a controldevice for controlling the hydraulic transmission, the control devicecomprising an hydraulic control valve operable by a control memberhaving a plurality of operating positions, each of which corresponds toa position of the control valve which is effective to supply pressurizedfluid to one of the clutches, the control member also having a neutralposition corresponding to a position in which the control valve does notsupply pressurized fluid to any of the clutches, and locking means whichis arranged to lock the control member in the neutral position, andwhich, if moved to its locking position when the control member is inany one of the operating positions, acts to return the control member tothe neutral position and to lock the control member in the neutralposition.

According to a preferred embodiment of the present invention there isprovided a control device for an hydraulic system, the control devicecomprising an hydraulic control valve arranged to be operated by acontrol lever pivotable in a plane of movement containing a plurality ofoperating positions of the control lever and a neutral position of thecontrol lever intermediate two of the operating positions, each of theoperating positions of the control lever corresponding to an operatingposition of the control valve and the neutral position of the controllever corresponding to a neutral position of the control valve, and alocking means including a first member mounted on the control lever, anda second member pivotable for movement in a plane parallel to the planeof movement of the control lever, one of the first and second membersbeing a cam follower and the other of the first and second membersincluding opposed cam surfaces and a locating slot between the camsurfaces, whereby, when the second member of the locking means ispivoted while the control lever is in one of the operating positions,the cam follower will co-operate with one of the cam surfaces withconsequential pivotal movement of the control lever to the neutralposition thereof after which the cam follower may be caused to enter thelocating slot to effect locln'ng of the control lever in the neutralposition.

This preferred embodiment of the invention is particularly suitable foruse in tractors having an hydraulic transmission system with singleforward and reverse clutches selectable by a transmission control leverwhich is movable through an arc of a circle so that an hydraulic controlvalve is actuated to direct pressurized oil to either the forward or thereverse clutch. lnsuch a vehicle the control lever is usually arrangedto be at one end of its travel when one of the clutches is engaged, andat the other end when the alternative clutch is engaged. A positionmidway between theseextremes is adopted as the neutral position whenneither of the two clutches is supplied with pressurized oil and bothare therefore disengaged.

Advantageously the second member of the locking means in the controldevice according to the invention comprises a lock plate having opposedcam surfaces which are effective to direct a cam follower mounted on thecontrol lever into a locating slotbetween the cam surfaces when the lockplateis pivoted in the plane parallel to the plane of movement of thecontrol lever to lock the control lever in the neutral position.

The control device may be employed to control a system having the samenumber of operating positions on either. side of the neutral position,for example the tractor transmission system having a single operatingposition on either side of the neutral position, or the control systemmay be used to control a system having difi'erent numbers of operatingpositions on either side of the neutral position, for example a vehicletransmission system having two forward positions and a single reverseposition. In the embodiment which will be described the cam surfaces arestraight surfaces, but curved surfaces may be employed as an alternativein suitable circumstances.

The present invention also comprehends a vehicle including an hydraulictransmission having a plurality of hydraulically operable clutches forcausing forward and reverse movement of the vehicle and a control deviceas broadly described in the immediately preceding paragraphs forcontrolling the hydraulic transmission. Preferably the locking means isoperable to pivot the second member thereof by means of a locking leverwhich, in the unlocked position, blocks the exit of the vehicle operatorfrom the vehicle.

The invention will be better understood from the following detaileddescription of a preferred embodiment thereof which is made, by way ofexample, with reference to the accompanying schematic drawings, inwhich:

FIG. 1 is a line diagram showing a control device according to theinvention for controlling the hydraulic transmission of a vehicle havingsingle forward and reverse hydraulically operable clutches, the controldevice having the locking mechanism in the unlocked position;

FIG. 2 shows the control device of FIG. 1 with the locking means beingmoved to the locking position when the control lever is in an operatingposition, and

FIG. 3 shows a specific embodiment of the second member of the lockingmeans in which the second member comprises a lock plate.

Referring to the drawings and particularly to FIG. 1, there is shown acontrol lever 1 which is pivotable about the axis 2, and which includesan extension 3 on the further side of the pivot from a handle 4 by whichthe control lever is operated by the vehicle operator. The extension 3of the control lever l is connected by a link 5 to one end of a lever 6which is pivotable about an axis 7.

Rigidly connected to the lever 6, so as to pivot about the axis 7 withthe lever 6, is a selector arm 8 which extends inside a valve chest 9.The selector arm 8 is hollow and is'arranged to connect oil pressure toany one of the three positions marked as F, N and R in FIG. 1, F and Rbeing the connections to hydraulically operated forward and reverseclutches, and the position N being a middle blank position which is theneutral position when neither the forward nor reverse clutch isactuated.

The control lever l carries a pin 10 which constitutes one of themembers of the locking means. The remainder of the locking means isgenerally designated in FIG. 1 by the reference numeral 11, and isgenerally pivotable about an axis 12 which is parallel to the axis 2,about which the control lever l is pivotable.

The other member of the locking means is the locking member 13 which isdirectly pivotable about the axis 12, and which includes opposedstraight cam surfaces 14 and 15 with a locating slot 16 between them.The member 13 is rigidly connected at 17 to an operating handle 18 and aspring 19 is connected between the point of connection 17 of the member13 and the operating handle 18 and a fixed anchor point 20 on the metalframework of the vehicle. A stop 21 limits the clockwise movement of themember 13 about the axis 12 under the action of the spring 19 when thelocking mechanism is not being used.

The operating handle 18 is preferably arranged in such a way that in theunused position of the locking mechanism the operating handle 18completely blocks the exit from the vehicle operators cab. Consequentlythe operator has to move the operating handle 18 in order to lock thecontrol lever in the neutral position, in the manner which will bedescribed, before the operator can dismount from the vehicle cab.

Referring now to FIG. 2, the control lever l is shown pivoted clockwisethrough a small angle from the neutral position so that oil pressure isfed by the selector arm 8 to the port F of the forward clutch. Also inFIG. 2 the operating handle 18 is shown raised in order to permit theoperator to leave the vehicle cab. As a result of the raising of theoperating handle 18 the member 13 is pivoted anti-clockwise about theaxis 12 so that the point 17 on the member 13 is moved to the positionshown in FIG. 2, where spring 19 is efiective to urge the member 13 tocontinue movement in the anticlockwise direction and to assist incompleting the locking action which, in this case, is effected by thecam surface 14 and the locating slot 16.

During anticlockwise movement of the member 13 about the axis 12 withthe control lever l in the forward position the cam surface 14 comesinto engagement with the pin 10 which acts as a cam follower, and whichis forced to move along the cam surface 14 in the direction of the slot16. Consequently the control lever l is forced to move in ananticlockwise direction about the axis 2 with consequential movement ofthe selector arm 8 from connection with the port F of the forward clutchtowards the neutral or blank position N.

The movement of the member 13 of the locking mechanism in ananticlockwise direction about the pivot 12 continues until the pin 10 isforced to enter the locating slot 16, at which time the control lever 1is in the neutral position in which it has moved the selector arm 8 backto the midposition N which was shown in FIG. 1.

If the control lever l is in the reverse position movement of theoperating handle 18 and the member 13 to lock the control device willbring the cam surface 15 into engagement'with the pin 10, which willthen be directed by the cam surface 15 into the locating slot 16 wherethe pin 10 is locked until apositive movement by the operator moves theoperating handle 18 back to the unused position shown in FIG. 1, and soreleases the pin 10 so that the control lever 1 may be moved to selectthe forward or reverse clutch. L

When the control device is locked by location of the pin 10 in the slot16 accidental movement of the control lever l, for example by theoperator contacting it when mounting or dismounting, is prevented.

Also in some vehicles it is possible to stop forward or reverse movementby reducing the engine speed until the torque converter no longertransmits the necessary power. In such a case the operator is notobliged to return the control lever to the neutral position, and thevehicle would be liable to sudden movement as a result of inadvertentoperation of the throttle control. However, incorporation of a controldevice in accordance with the invention as described with reference tothe drawings accompanying the specification in such a vehicle would havethe effect of forcing the operator to lock the control lever in theneutral position before dismounting, and any subsequent accidentalmovement of the throttle control would not then cause the vehicle tomove unintentionally.

The member 13 of the locking means is preferably made as a lock plate,having cam surfaces 14 and 15 with a locating slot 16 between them asshown in FIG. 3

It will be understood that the detailed apparatus may be modified inmany ways within the ambit of the present invention, and in particular aroller may be incorporated on the'pin in order to facilitate movement ofthe pin 10 over a respective one of the cam surfaces 14 and 15.Conveniently the control lever 1 and the member 13 are both pivoted onthe same part of the vehicle framework, and because their axes of pivot2 and 12 are parallel the control lever l and the member 13 will move inplanes parallel to one another.

The embodiments of the invention for which an exclusive property orprivilege is claimed are defined as follows:

1. A control device for an hydraulic system, the control devicecomprising an hydraulic control valve arranged to be operated by acontrol lever pivotable in a plane of movement containing a plurality ofoperating positions of the control lever and a neutral position of thecontrol lever intermediate two of the operating positions, each of theoperating positions of the control lever corresponding to an operatingposition of the control valve and the neutral position of the controllever corresponding to a neutral position of the control valve, and alocking means including a first member mounted on the control lever, anda second member pivotable for movement in a plane parallel to the planeof movement of the control lever, one of the first and second membersbeing a cam follower and the other of the that and second membersincluding opposed cam surfaces and a locating slot between the camsurfaces, whereby, when the second member of the locking means ispivoted while the control lever is in one of the operating positions,the cam follower will cooperate with one of the cam surfaces withconsequential pivotal movement of the control lever to the neutralposition thereof after which the cam follower may be caused to enter thelocating slot to effect locking of the control lever in the neutralposition.

2. A control device according to claim 3, wherein the second member ofthe locking means comprises a lock plate having said opposed camsurfaces which are effective to direct said cam follower mounted on thecontrol lever into a said locating slot between the cam surfaces whenthe lock plate is pivoted in the plane parallel to the plane of movementof the control lever to lock the control lever in the neutral position.

3. A control device according to claim 3 wherein the cam surfaces arestraight surfaces.

4. A control device according to any one of claim 3, wherein the controllever has single forward and reverse operating positions on either sideof the neutral position.

* l l= II!

1. A control device for an hydraulic system, the control devicecomprising an hydraulic control valve arranged to be operated by acontrol lever pivotable in a plane of movement containing a plurality ofoperating positions of the control lever and a neutral position of thecontrol lever intermediate two of the operating positions, each of theoperating positions of the control lever corresponding to an operatingposition of the control valve and the neutral position of the controllever corresponding to a neutral position of the control valve, and alocking means including a first member mounted on the control lever, anda second member pivotable for movement in a plane parallel to the planeof movement of the control lever, one of the first and second membersbeing a cam follower and the other of the first and second membersincluding opposed cam surfaces and a locating slot between the camsurfaces, whereby, when the second member of the locking means ispivoted while the control lever is in one of the operating positions,the cam follower will cooperate with one of the cam surfaces withconsequential pivotal movement of the control lever to the neutralposition thereof after which the cam follower may be caused to enter thelocating slot to effect locking of the control lever in the neutralposition.
 2. A control device according to claim 3, wherein the secondmember of the locking means comprises a lock plate having said opposedcam surfaces which are effective to direct said cam follower mounted onthe control lever into a said locating slot between the cam surfaceswhen the lock plate is pivoted in the plane parallel to the plane ofmovement of the control lever to lock the control lever in the neutralposition.
 3. A control device according to claim 3 wherein the camsurfaces are straight surfaces.
 4. A control device according to any oneof claim 3, wherein the control lever has single forward and reverseoperating positions on either side of the neutral position.